Great article. MVO is designed to optimise a portfolio only if the goal of investing is to maximise the Sharpe Ratio (its an "asset only" asset allocation approach. If the goal of investing is not to maximise the Sharpe Ratio but is instead to meet ongoing liabilities (like in your example the average client) then an "asset only" approach is not appropriate but instead an Asset Liability approach should be used. The technical reason is that an "asset only" approach like MVO includes the Mean, Std and correlations but ignores the sequencing of returns which is actually very important if you are funding liabilities.